there are plenty of scenario's we can rebuild in Cisco's Packettracer.

everyone brings a networking idea to the group and presents it as a challenge for the group to solve.

to sharpen the troubleshooting skills, we need unforeseen troubles. Perhaps, in turn, one could be the troublemaker. (such as tampering with the cables, settings, and other kinds of mayhem ;-)

more proposals

...

Little project ideas

Mostly useless projects, but fun for who's into tcp segments, ip packets, ethernet frames and bits (<-- terms are usefull for CCNA exam, atleast one has spotted the error ;-)
Most can be tested in Cisco's Packet Tracer.

How to make an infinite loop (well at least as long as the TTL of a packet isn't zero)

Would it be possible to ping the next door computer but first route the packets around the world?

If routing around the world has succeeded, could we collide the packets then? (So in fact we would have made the Large Ping Collider ;-)